Blower cooling means for air cooled engines



Sept. 26, 1939. F. w. CALDWELL 2,173,896

BLOWER COOLING MEANS FOR AIR COOLED ENGINES Filed Nov. 20, 1955 '3 Sheets-Sheet 1 N INVENTOR.

- I E 517]! WLT'BHllE/f BY L57 Z ATTORNEY Sept. 26, 1939. F. w. CALDWELL 2,173,396

BLOWER COOLING MEANS FOR AIR COOLED ENGINES Filed Nov. 20, 1935 3 Sheets-Sheet 2 INVENTOR.

A TTORNEY Sept. 26, 1939. F. w. CALDWELL BLOWER COOLING MEANS FOR AIR COOLED ENGINES Filed Nov. 20, 1935 3 Sheets-Sheet 3 I N V EN TOR. Frank W1: bill/B1] 2 ATTORNEY Patented Sept. 26, 1939 BLOWER. COOLING MEANS Fort AIR. COOLED ENGINES Frank W. Caldwell, Hartford, Conn., assllnor to United Aircraft Corporation, Conn, a corporation of Delaware East Hartford,

Application November 20, 1935, Serial No. 50,672

10 Claims.

This invention relates to blower cooling means for air cooled engines and has particular reference to cooling means adapted for use with engines such as are employed to furnish motive power for airplanes or other vehicles.

An object of the invention resides in providing in combination with a cowledengine equipped with air pressure baffles, an air blower for materially increasing the pressure of the air within the high pressure chamber of the engine cowl.

A further object resides in the provision of a blower so designed that it is efficient at engine speeds and may therefore be connected directly to the engine power shaft or to a propeller driven thereby.

A still further object resides in the provision of means for properly directly the air supplied by the blower to the cooling surfaces of the engine cylinders.

Other objects and advantages will be more specifically pointed out hereinafter, or will become apparent as the description proceeds. v

In the accompanying drawings in which like reference numerals are used to designate similar parts throughout there is illustrated a suitable mechanical embodiment of what is now considered to be the preferred form of the invention.

The drawings, however, are for the purpose of illustration only and are not to be taken as limiting the invention, the scope of which is to be measured entirely by the scope of the appended claims.

In the drawings, Fig. l is an elevational view of that portion of an airplane in which the engine is mounted, certain portions of the airplane being broken away to show the means for air cooling the engine, and a portion of the blower being shown in section to better illustrate the construction thereof.

Fig. 2 is a rear elevational view of a fragmentary portion of the air directing device illustrated in section in Fig. 1.

Fig. 3 is a sectional view on the line 3-3 of Fig. 5.

Fig. 4 is a sectional view on the line 4-4 of Fig. 5.

Fig. 5 is a front elevational view of the improved engine cooling blower.

Referring to the drawings in detail the numeral Ill generally indicates an engine which may be mounted upon the forward end of an airplane fuselage generally indicated at 12. The engine is provided with a crankcase 14 upon which is mounted a plurality of radially disposed cylinders IS, the engine illustrated having two banks of cylinders arranged in parallel rows around the engine crankcase. A power shaft l8 projects from the forward portion of the crank case and upon this shaft there is mounted a propeller generally indicated at 20 having a hub 22, the outer portion of which comprises a split barrel member 24, the two halves of which are clamped together and secured upon the propeller hub by means of clamp bolts 26 passing through apertured ears 28 formed on the barrel adjacent to the adjoin- 1 ing edges of the two halv The engine is enclosed in a stream lined, drag reducing, cowl 30 having at its front end an air inlet aperture 32, and at its rear end an air outlet vent or gill opening 34. If desired, the outlet 15 vent or gill opening 34 may be controlled by a group of adjustable cowl trailing edge flaps 36 operated by a manual control 38 which extends from the flaps to the operator's compartment of the airplane or other vehicle upon which the en- Sine is mounted.

Within the cowl the spaces between the various engine cylinders are blocked by air pressure baffles 40 which limit the amount of air flowing through the engine substantially to that flowing 25 between adjacent cooling fins upon the engine cylinders so that a higher pressure will be maintained in that portion of the cowl upon the air inlet side of the baflles 40 than within the portion of the cowl upon the air outlet side of the baffles. 30 The action of the flaps 36 is such that when extended the flaps reduce the pressure in the low air pressure portion of the cowl and thereby increase the velocity of the air flowing past the engine cooling fins.

The combination of the pressure baflles and cowl trailing edge flaps has been found to provide satisfactory cooling in substantially all installations when the airplane upon which they are mounted is in flight. In certain types of air- 4: planes, however, there are periods during its use during which the air velocity or slipstream past the airplane is not suflicient to provide an adequate amount of air for engine cooling. Such periods occur when the engine is operating while 45 the airplane is on the ground or taxiing, and may also occur to a somewhat lesser extent when an airplane provided with a high lift wing flap is making a rapid climb, that is when most of the engine power is being used to gain altitude and the consequent forward speed of the airplane is relatively low. Under these special circumstances it has been found desirable to provide additional means for obtaining a differential value of air pressure upon the two sides of the baiiles 40, and

for this purpose there has been provided the improved air pressure blower particularly illustrated in the accompanying drawings.

A mounting disc 42 is secured upon the power shaft. I8 in concentric relation therewith and against relative rotation preferably by extending the barrel clamp bolts 28 to engage in spaced apertures 44 provided in the inner portion of the mountlngdisc, this-connection being particularly illustrated in Fig. 4. The disc is reinforced around the apertures 44 by reinforcing rings 48 and 48 secured to the disc by means of rivets 50 passing through aligned apertures in the rings and the disc. While the rivets 50 have been found to be satisfactory meansfor securing the reinforced rings to the disc, it is to be understood that other suitable means such as welding or brazing may be employed without departing in any way from the scope of the invention.

In order to provide a resilient or vibration absorbing connection between the propeller and the rotor mounting disc 42, the aperture 44 is made with a diameter greater than the diameter of the extended portion 52 of the bolt 28 which passes through the aperture. At the beginning of the extension 52 the bolt is provided with an enlarged radially extending flange 54 and a rubber bushing 56 is disposed between the flange 54 and the adjacent surface of the disc 42 surrounding the extension 52 of the bolt, the rubber bushing being of such exterior dimensions that a portion thereof is compressed into the reinforcing ring 48 as indicated at 5 8. A similar bushing 80 is disposed upon the opposite side of the rotor mounting disc 42 from the bushing 55 and is forced into compression in the reinforcing ring 46 by means of a washer 62. The two bushings 55 and 80 are maintained compressed in rotor supporting condition by means of a nut 64 screw threaded upon the end of the bolt extension 52 opposite the flange 54. One or more of the mounting connections as described above will be provided at each blade joint of the propeller. The rotor supporting disc 42 is provided with an enlarged concentric aperture 66 surrounding the engine power shaft I8 and the space between the inner circumference of the rotor supporting disc and the outer surfaceof the power shaft is sealed by a thin flexible plate member 68 secured to the disc 42 by being clamped between the reinforcing rings 48 and the adjacent surface of the disc.

The outer edge of the rotor supporting disc 42 defines the inner circumference of the inlet opening 10 through which the air is drawn into the rotor or blower. The outer edge of this air inlet opening 10 is defined by the headed over inner edge I2 of a disc or ring member I4 which extends from the edge of the air inlet opening to a position within or adjacent to the nose piece 16 of the cowl so thatthe passage of air through the cowl aperture 32 is blocked off by the rotor except for the relatively narrow air inlet opening 10 provided in the rotor. A ring member I8 of channel section is secured to the disc 42 in a position such that it surrounds the aperture 68. This ring member I8 projects axially inward from the disc 42, as particularly illustrated in Fig. 1, and at its rearward edge is connected to a backing plate 80 in the form of an apertured disc which is positioned substantially parallel to the disc 42 and spaced rearwardly therefrom. The backing plate 80 extends radially from the rearward edge of the ring member I8 to a position within the nose piece I8 of the cowl substantially in axial alignment with the outer edge of the front disc member 14.

Between the front members 42 and I4 and the rear member or backing plate 80, the rotor is provided with a plurality of substantially radially extending vanes 82 illustrated in section in Fig. 3. These vanes 82 are preferably formed of sheet metal to an angular section as illustrated in Fig. 3 and have angle members 84 and 88 welded thereto along opposite edges to provide a member of built up substantially I section. The vanes 82 extend from the ring member 18 to the outer circumferences of the disc members I4 and 82 and, as illustrated in Fig. 3, are disposed at an angle to the plane of rotation of the rotor so that they are disposed diagonally across the space between the members I4 and 42 and the backing member 80 and are secured to the front and back disc members of the rotor by having the flanges of the I section welded or otherwise suitably secured to the disc members. These vanes are also preferably curved in a radial direction to provide spiral airflow passages between adjacent vanes, the spiral curving being in a direction opposite to the rotation of the rotor.

From the above description it will be observed that the rotor comprises a blower of the centrifugal type in which the air is taken in near the center of the rotor and whirled through a relatively long, radially extending air passage so that the mass of the air is acted upon by centrifugal force due to the rotation of the blower to force the air at high pressure out of the circumferential ends of the radial air passages. This type of blower tends to develop a high static air pressure in the space adjacent its exit instead of merely increasing the velocity of air flowing therethrough.

Within the nose piece 15 and adjacent the outer circumference or air exit of the rotor, there is disposed an air directing device generally indicated at 88. This device comprises an outer sectionally curved annular member 80 lying within and substantially parallel to the nose piece 18, an inner sectionally curved annular member 92 spaced radially inward from and rearwardly of the member 80, and a plurality of spaced radially extending air directing bailles 94 between the annular members 80 and 92. The air directing member 88 is secured to the nose piece 18 by means of resilient connections as indicated at 88, but is supported chiefly by a conical or dished disc member 88 which is connected at its outer circumferential edge to the forward edge of the inner annular member 92 as indicated at I00 and is apertured to receive the nose portion of the engine crankcase I4 and rigidly secured to the engine by being inserted under the heads of the engine nose section cap screws I02. At its engine connected edge the member 88 may be reinforced by being welded as indicated at I04 to a ring member I06 having a relatively thick cross section which is apertured adjacent its inner edge to receive the cap screws I02.

The annular members 90 and 82 are curved to provide a flared air duct leading from the air exit of the rotor to the interior of the cowl 30, the widest portion of the flare being at the air exit of the air directing member as particularly illustrated in Fig. 1.

The air directing vanes 84 are preferably formed of sheet metal to provide members of Z section having along opposite edges, flanges which may be welded, riveted, or otherwise rigidly secured to the respective annular members 88 and aivaaoe 92 and are disposed radially of the space between the two annular members 90 and 92, but are inclined or curved in an axial direction to correspond to the'direction of the air stream issuing from the exit portion of the rotor to avoid dissipatizig any portion of the pressure and velocity ofthe air by suddenly changing its direction of flow.

From the air directing member 82, the air issues into the space within the cowl upon the air inlet side of the pressure baifles 40 and because of the difference in air pressure maintained upon the opposite sides of these battles, the airthen flows between the bafiles and the engine cooling surfaces to the space within the cowl upon the opposite sideof the baflles and from this space vented through the cowl gill opening 34.

From the above description it will be observed that there has been provided a simple and effective form of air blower designed to increase the pressure of the air flowing therethrough, such blower being particularly adapted for use with an engine cooling system which depends upon differences of air pressure upon two opposite sides of the engine to obtain the necessary cooling effect from the air supplied to the engine cooling system.

While there has been illustrated and described a particular mechanical embodiment of the idea of the invention, it is to be understood that the invention is not limited to the particular mechanical embodiment so illustrated and described, but that such changes in the size, shape and arrangement of parts may be resorted to as come within the scope of the appended claims.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

What is claimed is:

1. In combination with an air cooled engine having a power shaft, means. for increasing the flow of cooling air to said engine, said means comprising, a centrifugal rotor mounted on said power shaft having an air inlet adjacent to its axis of rotation and a radially directed air outlet at its periphery, and an annular air directing device encircling said rotor.

2. In combination with an air cooled engine having a" power shaft, a centrifugal blower mounted on said power shaft for increasing the flow of cooling air to said engine, said blower comprising, a rotor having an annular air inlet opening adjacent to its axis of rotation, an air outlet opening at its periphery, and radially directed elongated air passages between said inlet opening and said outlet opening, and an annular air directing device encircling said rotor.

3. In combination with an air cooled engine having a power shaft, and a propeller mounted on said power shaft, means for increasing the flow of cooling air to said engine comprising, a centrifugally acting rotor secured to said propeller for rotation therewith and provided withv radially directed air passages extending from a location adjacent the axis of rotation of said rotor to the periphery thereof, and an annular air directing device encircling said rotor.

4. In combination with a cowled air cooled engine having a power shaft, means for increasing the flow of cooling air to said engine comprising, a rotor mounted on said power shaft for rotation therewith and comprising front members, a back member, and a plurality of radially directed vanes between said front memhers and said back member, a device for directing air from the periphery of said rotor comprising an outer annular member, an inner annular member, and a plurality of baflles between said inner and said outer members encircling said rotor and disposed within the nose piece of said cowl.

5. In combination with an air cooled engine having a power shaft, an open ended cowl encircling said engine, and pressure baflies forming with said engine a partition dividing the interior of said cowl into a high air pressure chamber and a low air pressure chamber, means for increasing the air pressure in said high air pressure chamber comprising, a rotor having radially directed air passages venting at its periphery mounted on said power shaft for rotation therewith, and a device having a plurality of radially'extending passages and encircling, close to, and concentric with the periphery of said rotor for directing the air from the periphery of said rotor into said high pressure chamber.

6. In combination with an air cooled engine having a power shaft, an open ended cowl encircling said engine, and pressure baflles forming with said engine a partition dividing the interior of said cowl into a high air pressure chamber and a low air pressure chamber, means for increasing the air pressure in said high air pressure chamber comprising, a rotor having radially directed air passages venting at its periphery mounted on said power shaft for rotation therewith, and a device for directing the air from the periphery of said rotor into said high pressure chamber, said air directing device comprising, an outer annular member of curved 35 cross section disposed within the nose piece of said cowl, an inner annular member of curved cross section spaced inwardly and rearwardly from said outer annular member, the curvature of said members being such as to change the direction of air flow from substantially radial to substantially axial, and a plurality of radially disposed baflies between said inner and outer members inclined with respect to the axis of rotation of said rotor.

'7. In combination with an air cooled engine having a crankcase including a nose section, and a power shaft projecting from said nose section, means for increasing the flow of cooling air to said engine comprising, a centrifugal rotor mounted on said power shaft for rotation therewith, an air directing device comprising curved outer and inner annular members and spaced baflies between said annular members encircling said rotor, and a dished disc member apertured to receive the nose section of said engine secured to said crankcase and said air directing device to support said air directing device upon said engine and provide an air seal between said air directing device and said engine.

8. In combination with an air cooled engine having a power shaft, an open ended cowl encircling said engine, and pressure baflies forming with said engine a. partition dividing the interior of said cowl into a high air pressure chamber and a low air pressure chamber, means for increasing the air pressure in said high air pressure chamber comprising, a rotor having radially directed air passages venting at its periphery mounted on said power shaft for rotation therewith, and a device for directing the air from the periphery of said rotor into said high pressure chamber, said air directing device comprising, an

outer annular member of curved cross section 4 ai'rasoc disposed within the nose piece of said cowl, an inner annular member 01' curved cross section spaced inwardly and rearwardly from said outer annular member, the curvature oi said members being such as to change the direction of air flow from substantially radial to substantially axial, and a plurality of radially disposed bailles between said outer and said inner annular mem- 9. The combination with an engine having a propeller, of cowling having an inturned leading edge rearward of the propeller defining an air entrance, divergent diiluser vanes secured within said inturned edge, and a blower secured for rotation with the propeller and lying wholly rearward thereof and having peripheral vanes within the cowl leading edge organized to discharge alr substantially radially into said diti'user.

- 10. The combinationwith an engine having a propeller, o! ablower secured to the back of the propeller, said blower having peripheral substantially radially outwardly discharging vanes surrounding a central air entrance, a rearwardly extending difluser cowl embracing the blower having its leading edge inwardly curved and substantially radially aligned with the forward edges 0! said vanes in the plane of rotation thereof, said diiluser receiving substantially radially discharged air from said blower and, by its leading edge curvature, changing the direction 0! the air flow from a substantially radial to a substantially axial direction, vanes in said difluser adjacent the leading edge thereof for guiding air flow therethrough, and a ring cowl embracing the engine, forming a rearward prolongation of said-difluser cowl for confining air delivered by said blower to the region or said engine.

FRANK W. CALDWELL. 

